If the United States were to fall, would it be from an outside force or because we destroyed ourselves from the inside?

I think it's pretty clear that no one entity has the power to destroy America. Now we may weaken ourselves to the point where another nation could deliver the final blow, but the actual cause will be a rotting at the core (and we can already see the occurring). How can we expect children who are indoctrinated to hate America and taught to fear their own shadows, defend the nation?

I believe both ways if we don't come together.

The answer to this question is obvious. We have a bad habit of making things worse than they have to be. If we fall it will because we did it to ourselves.